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Flora Fact: Turtle Grass

This plain-looking seagrass helps prevent erosion during hurricanes and serves as food and shelter for marine life.

By Sheryl Smith-Rodgers

If you've ever fished the Texas coast, then you've likely encountered submerged beds of turtle grass (Thalassia testudinum), covered with silt and algae. At first glance, those long, broad blades of green may seem mundane. Not so. Within their depths lies a critical underwater habitat that teems with dynamic life.

Turtle grass — one of five seagrass genera found along the Gulf Coast — thrives in the shallow waters of most bays and estuaries south of Rockport. Farther north, sparse populations grow as far as Galveston Bay. Between Rockport and Aransas Pass, a huge continuous meadow of turtle grass occurs in Redfish Bay, where state law prohibits its destruction by boat propellers.

As a fruit bearer, turtle grass nodes — which bear two to five 14-inch-long leaves — produce pale white or pink flowers during spring and summer. The round, pod-like seeds aid little in reproduction, though. The plants largely spread through underground horizontal runners called rhizomes. Anchored by thick roots, this extensive network of shoots stabilizes the ocean floor and prevents erosion, especially during storms and hurricanes.

Up above, the undersea grass beds conceal and feed scores of marine animals. At the bottom of the food chain, microscopic organisms, algae, worms and sponges attach to the flat leaves, creating a smorgasbord for larger critters. Shrimp, crabs and juvenile game fish hide out in the grass. Predators waiting to ambush prey do, too. Green sea turtles (Chelonia mydas) — an endangered species measuring 3 feet or longer — graze the plant, hence the common name of "turtle grass."